Hi guys, I have a 91 bird, v6 3.1l auto. It runs, but it will die very quickly, usually not even 10 seconds after. Let me give you some background. It was a very hot day and I was driving my bird a lot more than I normally would, pretty much all day long. Did a few burnouts here and there. It was all fine until I took it home and shut it off. I came back out probably 10 minutes or so later, turned it on and it sounded horrible, idling very rough and coughy. The rpms were up to about 1000 - 1500 at idle. When I press the gas the rpms drop and it dies or starts to die but doesnt. Let it cool off and then it was fine. Ran great. Let it heat up, turn it off, turn it back on and it starts having the same problem. Now it won't even run fine after it cools off. It does it all the time. It idels erractically, like 500 to 1000, back to 600, to 1300 etc. Runs but will die soon after start up at idle, touch gas it dies, if I start it up and shift into reverse, drive, 1st, etc. It will run a lot longer before it dies, it just wont die right away. I replaced my MAP, checked the EGR, the IAC, replaced the TPS, replaced the ignition coil, the ignition module, checked timing, fuel pump, fuel pressure, and it still won't work. Help me

 

Have you checked the vacuum lines and hoses for leaks? Remove a couple of spark plugs and describe what color the tips are on the business end.

There is a TSB for the 91 regarding the ignition circuit, but that may not apply here as the system doesn't have enough time to get hot before it dies.

 

I just recently started my 3.1 camaro auto like yours and drove it all day and now after a long day its having the same problem. Starts fine then gets very rough and eventually cuts out and only does it when its hot. Ive checked the fuel pressure and swapped inginition coils. Im honestly a V8TBI guy but i need to get this running for inspection. What sensor is used only when hot that would cause this problem. Closed loop vs Open loop sensors?

 

Do a search for "1991 V6 ignition system recall"... There is a fault in the ignition circuit that causes intermittent rough running and stalling when hot. The O2S is the only sensor that isn't used until the engine is hot, but it wouldn't cause this problem without a code.

 

Didnt find anything on this ignition recall. Any help would be great locating this.

 

https://www.thirdgen.org/forums/v6/8...-you-have.html

Took a bit to find it. It says that it's for cold running problems, but the things that cause this problem seem to get worse as the engine warms up.

 

That should be a sticky

 

I agree there. Especially since there seems to be more and more of this happening, and I thought this was weird when it happened to me. I swapped my old harness back in only to find NOTHING wrong with the newer harness. And yes, I'm still running on my old 87 MY harness, because I don't have the replacement 91 harness yet...

 

Well mine does it all the time now, so I dont think its when the engine got hot, I think it was something that was just going bad maybe, and now it just went all together. I started mine up the other day and if I shift to r,d,od,2,1, it will keep running but once I touch the gas, it acts like the fuels just been cut and stops, rpms drop, but if I take my foot off the gas it will start idling again. In park it idles at 1500 1000, in d,r,etc, it will idle right around 900-500

 

And someone emailed me saying that their 92 camaro with the same engine had the same problem and it ended up being the injector for cold startup was bad.

 

Well, that person was an idiot. Why? None of the V6 engines made between 90 and 92 even HAD a cold start injector. Cold starting is handled by newer code in the MEMCAL.

I'd check the voltage signal coming from your MAP and see if you are throwing any codes. Also check the TPS and the IAC for sticking. And check for vacuum leaks in the canister system... Seems like a ported vacuum leak.

 

I replaced the MAP sensor, don't know if that would have an effect on the voltage signal though and I replaced the TPS and checked the IAC, it works fine.

 

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Im still tracking down my problem. Seems to be fuel related for me. I will be pulling the manifold off and checking the fuel pressure regulator.

 

Did you check the voltage signals at the MAP and TPS? Did you get any codes from the ECM? Did you check for broken, loose, or degraded vacuum lines?

 

I cant seem to find my repair manaul. Can someone inform me of what the voltages or ohms should be for those sensors. I will check them just in case even though i swapped out everything but the MAP sensor. Ive already disconnected and blocked the HVAC line to the inside of the car cause one was leaking. Its really wierd cause if you start the car and let it idle it will not act up but only does it once you give it some throttle till it just knocks out. Restart the car and it acts totally fine. so wierd

 

I checked the spark plugs and they're straight black, like oil coated. I checked codes and got a 22 and 35 also. 22 is the TPS, which I replaced and 35 is the Idle Speed Control, so I'll take a look at that.

 

Are the black plugs wet or dry? If they're dry, they're carbon fouled due to WAY too much fuel in the chambers. Code 22 is TPS signal High, and code 35 (high, uncontrolled idle speed) is caused because of this (ECM can't force the idle speed down if it thinks that the throttle plate is partially open). One can't always slap a TPS on and call it a day... They may have a single screw hole, but they're designed so that slots can be cut into the mounts and they can be adjusted if need be.

 

I fixed my issues. Ended up having to swap the fuel rail and all 6 injectors to correct the issue. I'm thinking the fuel regulator was the culprit. Good thing I got a another fuel injection setup from the owner I bought the car from. :-)

 

The plugs are dry, and I checked again and the code 35 is pretty much for the TPS as well.

 

What is the voltage reading between the blue and black wires at the TPS?

 

im having prettymuch the same problems with my 1990 camaro rs 3.1 v6 originally i bought the car as a project car and knew there were problems but it was running really good i had to change the tranny mount and then shortly after moved to New york and drove the car from maine to ny with no problems then the alternator died so i changed that with a brand new ac delco and now there are all kinds of problems i had to change the plugs and wires i changed the distributer cap. i never changed or even opened the hood before i drove it here and it was a 350 mile drive i foudn that the idiot that i bought it off from didnt even have an air filter in it so i put that in and now it runs ok while in park still kinda rough but as soon as i put it into gear it stalls out of course the other day i was trying to change the vacumm lines because i heard that could be the problem and i broke the brake booster so i need to replace that but it seemed to even run better without the booster. what could be my problem if its not the vacumm lines?